This invention relates to the field of devices which releasably hold the face surfaces of two rigid sheets or panels in close proximity to one another. Particularly, it relates to a unitary device for use in such fastening applications where it is desirable to fasten two such panels together with a snap action and to unfasten and separate them quickly by rotation of a stud, the head of which is accessible at the outside surface of the panels.
In the prior art, fasteners which have been available to hold two panels together in face to face abutment usually have included one or more components adapted to be attached permanently to one or more of the panels to be fastened together. Fasteners of this type are shown in U.S. Pat. Nos. 2,853,114; 3,244,444; 3,862,773 and 3,204,680. Previous fasteners of the quarter turn type provide a fastening and unfastening action by means of a stud with a shaped end which cooperates with a separate receptacle. However, the stud and receptacle components each require a retainer or attachment means to hold them in position on the respective panels. The installation of such fastening devices requires several operations as well as additional attachment components and this increases the total cost of using such devices. Fasteners of this general type are shown in U.S. Pat. Nos. 1,955,740; 2,575,311 and 3,123,880.
The prior art also includes panel fasteners consisting of a single assembly to be installed in one of the panels and having a stud with radial extensions adapted to engage a shaped hole. In one position of rotation the projections on the inner end of the stud element pass through a cooperating shaped hole in the panel; in another position of rotation the stud projections engage the edge of the shaped hole after passing over detents. To operate this style fastener, the stud element must be pushed inward before it can be rotated past the detent elements that are required. In order to provide for the axial movement of the stud required to clear the detents, the head of the stud must project well above the outer panel surface and this substantial projection is objectionable in many applications.
Also included in the prior art are fasteners incorporating a rotatable stud which operates to compress a resilient sleeve thereby accomplishing a fastening action. A fastener of this type is shown in U.S. Pat. No. 3,673,913.